Sloped Roof Snow Loads Using Simulation

Abstract

Snow loads on sloped roofs are influenced by snow properties, meteorological factors, and building parameters. A statistical model of snow accumulation for unobstructed slippery roofs is developed. Sliding at the roofsnow interface is initiated by either a reduction in the resisting forces or shear failure; the latter involves a reduction in the shear resistance of the snowpack. Temperature, temperature‐time, and precipitation are used as independent variables to develop the conditional probabilities for sliding from field and laboratory data. Roof snow loads for a site in deep‐snow country are simulated using existing meteorological data to obtain probabilities of occurrence for temperature and precipitation. Simulated design loads are compared with values from ANSI A58.1‐1982 and the Idaho approach. Roof loads simulated from field and laboratory data demonstrate good agreement, but the two design approaches yield roof snow loads that are considerably higher than the simulated values.